CN107093794B - Array antenna for generating dual-mode vortex electromagnetic field - Google Patents

Abstract

The invention discloses an array antenna for generating a dual-mode vortex electromagnetic field, which mainly solves the problems in the prior art that the mode of the vortex electromagnetic field is single and the utilization rate of the array aperture is low. It includes 8 array units (T), feed network (K), dielectric substrate (J), coaxial probe (D) and metal floor (G), 8 array units (T) and feed network (K ) are printed on the upper surface of the dielectric substrate (J), and the metal floor (G) is printed on the lower surface of the dielectric substrate (J); the feed network (K) has an input port and 8 output ports, the input The end is connected to the coaxial probe (D) to realize the feeding of the coaxial probe (D) to the feed network (K); the 8 output ports are connected to the 8 array units (T) in sequence to realize The feed network (K) feeds the array unit (T). The invention can generate vortex electromagnetic waves in two modes, and can be used in the front end of a wireless communication system.

Description

Array antenna for generating dual-mode vortex electromagnetic fields

technical field

The invention belongs to the technical field of antennas, in particular to an array antenna for generating dual-mode vortex electromagnetic fields, which can be used in wireless communication systems, satellite communication systems and radar detection.

Background technique

Vortex electromagnetic waves are a type of electromagnetic waves different from ordinary plane waves. Plane waves only have spin angular momentum, while vortex electromagnetic waves not only have spin angular momentum, but also orbital angular momentum. It is distributed in a helical shape, which is different from the equiphase plane of the plane wave. Vortex electromagnetic waves can have different mode numbers l, and different l represents different degrees of vortex. In theory, l has infinitely many values, and different modes are orthogonal to each other. This feature provides an ideal development direction for improving spectrum utilization and channel capacity.

Through the tracking of the research status at home and abroad, it can be seen that scholars at home and abroad have proposed some methods of generating vortex electromagnetic fields, such as the literature "Q. Bai, A. Tennant and B. Allen. Experimental circular phased array for generating OAM radio beams [J ].Electronics Letters,25th September2014,Vol.50No.20:pp.1414–1415.”The method disclosed in the microstrip array antenna to generate a single-mode vortex electromagnetic field, which distributes 8 array elements at equal intervals concentrically On the circle, each array unit is sequentially connected to each output port of the feed network to form a circular array antenna to generate a single-mode vortex electromagnetic field. Although the array antenna formed by this method has high gain, low cross-section, and is easy to be conformal, the array antenna can only generate a single-mode vortex electromagnetic field, and cannot multiplex multiple modes at the same time. lower.

Contents of the invention

The object of the present invention is to address the shortcomings of the above-mentioned prior art and propose an array antenna for generating a dual-mode vortex electromagnetic field, so as to increase the number of modes for generating a vortex electromagnetic field and improve the aperture utilization of the array antenna.

In order to achieve the above object, the present invention is used to generate the array antenna of dual-mode vortex electromagnetic field, including 8 array units, feed network, dielectric substrate, coaxial probe and metal floor, and 8 array units and feed network are all Printed on the upper surface of the dielectric substrate, the metal floor is printed on the lower surface of the dielectric substrate, characterized in that:

Each array unit is an H-shaped patch, and one end of each H-shaped patch has a U-shaped groove on the surface, so that each array unit works at two frequency points of 0.9GHz and 1.8GHz;

There are two sets of dual stub impedance matchers in the feed network to make the feed network work at 0.9GHz and 1.8GHz;

There are also 8 differential-phase feed branches in the feed network to realize differential-phase feed between adjacent array units, that is, at the frequency point of 0.9GHz, these 8 differential-phase feed branches realize each phase in turn. The phase difference between the adjacent array units is 45°, and at the frequency point of 1.8 GHz, these eight phase-differential feed branches sequentially realize the phase difference between each adjacent array unit by 90°.

The above-mentioned array antenna is characterized in that: the feed network is provided with an input port and 8 output ports, and the input port is connected with the coaxial probe to realize the feeding of the coaxial probe to the feed network; the 8 output ports The ports are correspondingly connected to the 8 array units in turn, so as to realize the power feeding of the array units by the feed network.

The above-mentioned array antenna is characterized in that: the two sets of dual stub impedance matchers are 2 cascaded ladder-shaped impedance matchers, and the length of each section is λ _0.9 /6, wherein λ _0.9 is the corresponding working wavelength of 0.9GHz.

The above-mentioned array antenna is characterized in that: two sets of double-twig impedance matchers are located up and down at the position of the coaxial probe, and are symmetrical left and right.

The above-mentioned array antenna is characterized in that: the first transition branch and the second transition branch are up and down at the position of the coaxial probe, and left and right symmetrical.

The above-mentioned array antenna is characterized in that: it is characterized in that the eight differential-phase feeding branches are microstrip transmission lines with a serpentine structure, wherein, the first differential-phase feeding branch and the fifth differential-phase feeding branch, and the second differential-phase feeding branch The four pairs of differential phase feeders are the feeder branch and the sixth differential phase feeder branch, the third differential phase feeder branch and the seventh differential phase feeder branch, the fourth differential phase feeder branch and the eighth differential phase feeder branch The branches are symmetrical up and down at the position of the coaxial probe.

The above-mentioned array antenna is characterized in that: a tangent line with an inclination rate p is set outside the corner of each differential feed branch, the distance between the tangent line and the outside of the corner is L ₁ , and the angle between the tangent line and the bottom edge of the feed line is is 45°, the distance between the inside of the corner and the outside of the corner is L ₂ , and the bevel ratio p=L ₁ /L ₂ .

The above-mentioned array antenna is characterized in that: the first group of dual stub impedance matchers is provided with 2, the first transition stub is provided with 2, the second transition stub is provided with 4, and the second group of dual stub impedance matchers is provided with 4 , and every 2 transition branches are connected to form a pair.

The above-mentioned array antenna is characterized in that: the first group of 2 dual-stub impedance matchers, each of the first stubs is connected to each first transition stub, and each second stub is connected to each pair of the first transition stubs. The two transition branches are correspondingly connected, that is, the two second branches are respectively connected to the two pairs of transition branches; each of the two-branch impedance matchers of the second group corresponds to each of the first branches and each of the second transition branches Each of the second branches is connected to each pair of differential-phase feeding branches, that is, the four second branches are respectively connected to four pairs of differential-phase feeding branches.

The above-mentioned array antenna is characterized in that: the dimensions of the eight array elements are exactly the same, and they are distributed at equal intervals on a circle with a radius R, wherein R is a wavelength corresponding to 1.8 GHz.

Compared with prior art, the present invention has following advantage:

1. The present invention can generate a dual-mode vortex electromagnetic field under the same array aperture, which can realize the multiplexing of multiple modes of the vortex electromagnetic field, and improves the aperture utilization rate of the array antenna.

2. The present invention can work at two frequency points of 0.9GHz and 1.8GHz, increasing the working frequency bandwidth.

3. The present invention adopts the H-shaped microstrip antenna as the antenna array unit, which effectively reduces the size of the array unit and makes the structure of the formed array antenna more compact.

Description of drawings

Fig. 1 is the structural representation of the embodiment of the present invention;

Fig. 2 is the return loss curve figure of the embodiment of the present invention;

3 is a far-field radiation pattern with a vortex electromagnetic beam mode value of 1 at 0.9 GHz according to an embodiment of the present invention;

4 is a far-field radiation pattern with a vortex electromagnetic beam mode value of 2 at 1.8 GHz according to an embodiment of the present invention;

FIG. 5 is a near-field electric field distribution diagram of a vortex electromagnetic beam with a modal value of 1 at 0.9 GHz according to an embodiment of the present invention;

FIG. 6 is a near-field electric field distribution diagram of a vortex electromagnetic beam with a mode value of 2 at 1.8 GHz according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in further detail below in conjunction with accompanying drawings:

Referring to Fig. 1, the present invention is mainly composed of 8 array units T, feed network K, dielectric substrate J, coaxial probe D and metal floor G, and the 8 array units T and feed network K are all printed on the dielectric substrate On the upper surface of J, the metal floor G is printed on the lower surface of the dielectric substrate J, and the coaxial probe D passes through the metal floor G and the dielectric substrate J in turn, and is connected to the input port of the feeding network K, where:

The metal floor G adopts copper plate.

The dielectric substrate J is made of epoxy resin, the dielectric constant of this material is 4.2, the thickness of the dielectric substrate J is 5mm, and the length and width are both 500mm.

The array unit T adopts H-shaped patches, each unit has a length of L ₀ =70 mm and a width of W ₀ =74 mm; a first rectangular slot is opened at the center of both sides of each unit, and at the bottom of each unit A second rectangular slot is opened at the center of the side, and a U-shaped slot is opened at one end of each unit.

The feed network K includes a first set of dual stub impedance matchers 2, 3, a second set of dual stub impedance matchers 5, 6, a first transition stub 1, a second transition stub 4, and 8 differential phase feeders Branches 7, 8, 9, 10, 11, 12, 13, 14, among them, the differential phase feeding branches 7 and 8 constitute the first pair of differential phase feeding branches, and the differential phase feeding branches 9 and 10 constitute the second pair of differential Phase feed branches, differential phase feed branches 11, 12 constitute the third pair of differential phase feed branches, and differential phase feed branches 13, 14 constitute the fourth pair of differential phase feed branches; the first group of double branch impedance matchers 2 , 3 is provided with 2, the second group of dual-branch impedance matching devices 5, 6 is provided with 4, the first transition branch 1 is provided with 2, the second transition branch 4 is provided with 4, and every 2 second transition branches 4 connected to form a pair;

The first group of dual-stub impedance matchers 2, 3 and the second group of dual-stub impedance matchers 5, 6 all use 2 cascaded ladder-shaped impedance matchers, and the first group of dual-stub impedance matchers 2, 3 and The second group of double-twig impedance matchers 5, 6 are symmetrical up and down at the position of the coaxial probe D; the first transition branch 1 and the second transition branch 4 are all adopted as microstrip transmission lines with a rectangular structure, and the first transition The branch 1 and the second transition branch 4 are symmetrical up and down at the position of the coaxial probe D; the eight differential phase feeding branches 7, 8, 9, 10, 11, 12, 13, and 14 are all serpentine structures Microstrip transmission line, wherein, the first differential phase feeding branch 7 and the fifth differential phase feeding branch 11, the second differential phase feeding branch 8 and the sixth differential phase feeding branch 12, the third differential phase feeding branch 9 The four pairs of differential phase feeding branches 13, the fourth differential phase feeding branch 10 and the eighth differential phase feeding branch 14 are symmetrical up and down at the position of the coaxial probe D; The corner of the phase feed branch is provided with a tangent line with a bevel rate p, wherein the distance between the tangent line and the outside of the corner is L ₁ and the angle between the bottom edge of the feeder line is 45°, and the distance between the inside of the corner and the outside of the corner is The distance is L ₂ , and the inclination rate p=L ₁ /L ₂ . The connections of these components are as follows:

In the first group of dual-stub impedance matching devices 2, 3, each of the first stubs 2 is correspondingly connected to each of the first transition stubs 1, and each of its second stubs 3 is correspondingly connected to each pair of second transition stubs 4, namely The two second branches 3 are correspondingly connected with two pairs of second transition branches 4;

The second group of dual-stub impedance matchers 5, 6, each of its first stubs 5 is correspondingly connected to each of the second transition stubs 4, and each of its second stubs 6 is correspondingly connected to each pair of differential phase feeding stubs, that is Two differential-phase feeding branches are connected at one end to form a pair of differential-phase feeding branches, and are connected to the center of the end of the second branch 6 at the connection, so as to realize the connection between each second branch 6 and each pair of differential-phase feeding branches. Corresponding connection, and then four second branches 6 are respectively connected with the first pair of differential phase feeding branches 7, 8, the second pair of differential phase feeding branches 9, 10, the third pair of differential phase feeding branches 11, 12, the third pair of differential phase feeding branches Four pairs of differential-phase feeding stubs 13 and 14 are connected correspondingly;

In order to ensure that the output impedance of the eight output ports of the feed network K matches the input impedance of the array unit T, each differential phase feed branch of the feed network K needs to be deep into the second rectangle of each array unit T The inside of the slot is connected to the center of the top edge of the second rectangular slot; the 8 array units T are connected to the 8 output ports of the feed network K in turn, and the 8 array units T are equally spaced on the circumference of the radius R=166mm .

The slot parameters of the above-mentioned H-shaped patch, the parameters of the double-stub impedance matching device of the feed network K, the parameters of the transition stubs, and the skew rate of the differential-phase feed stubs and the width of the output port are all calculated according to the microstrip antenna theory. For optimization settings, this embodiment adopts, but is not limited to, the following parameters:

The first rectangular groove length d=35mm, width s=10.5mm; second rectangular groove length L _m =31.5mm, width W _m =6.85mm; U-shaped groove length L _s =16mm, width W _s =3mm, wherein, The distance between the U-shaped groove and the edge of the unit is df = 1mm; the width of the 8 ports of the feed network K is W _f = 4.85mm;

The widths of two sets of double stub impedance matchers 2 and 3 are 6mm and 12.6mm, and the lengths are 40.3mm and 13mm respectively; the widths of transition stubs 1 and 4 are both 9mm, and the lengths are 10mm and 17mm respectively; 8 differential phase feed The oblique cutting ratios of electrical branches 7, 8, 9, 10, 11, 12, 13, and 14 are p1=0.92, p2=0.95, p3=0.85, p4=0.85, p5=0.92, p6=0.95, p7=0.85 , p8=0.85.

In this embodiment, 8 array units T are fed with equal amplitude and phase difference through the feed network K, and the phase difference between adjacent array units T is Where N=8, l is the modal value of the vortex electromagnetic beam, and must satisfy 0<l<N/2. A reasonable phase difference between adjacent array units T can be achieved by adjusting the lengths of the differential phase feed branches 7, 8, 9, 10, 11, 12, 13, and 14

At 0.9GHz, the lengths of the four phase-differential feed stubs 7, 8, 9, and 10 in the upper part of the array antenna increase in turn by λ _0.9 /8, where λ _0.9 is the working wavelength corresponding to 0.9GHz, so as to realize the four The output phase difference of phase-differential feeding stubs 7, 8, 9, and 10 is 45°; since the upper half of the array antenna and its lower half are symmetrical about the location of the coaxial probe D, the four phase difference phases of the lower half of the array antenna The output phase difference of the feed branches 11, 12, 13, 14 is the same as the output phase difference of the 4 different-phase feed branches 7, 8, 9, 10 in the upper half, that is, the 4 phase-differences of the lower half of the array antenna The output phase difference of feed branches 11, 12, 13, and 14 is also 45°; according to the mirror image principle, the output phase difference between the output phase of the fifth differential-phase feed branch 11 and the output phase difference of the first differential-phase feed branch 7 is 180°, the output phase difference of the sixth phase-differential feeding branch 12 and the output phase of the second differential-phase feeding branch 8 is 180°, the output phase of the seventh differential-phase feeding branch 13 is different from the third The phase difference between the output phases of the phase feed branch 9 is 180°, and the output phase difference between the eighth phase difference feed branch 14 and the output phase of the fourth phase difference feed branch 10 is 180°.

In summary, the output phase differences of the 8 differential phase feed branches 7, 8, 9, 10, 11, 12, 13, and 14 are all Since the 8 phase difference feed branches 7, 8, 9, 10, 11, 12, 13, and 14 are respectively connected to 8 array units T, the phase difference between adjacent array units T is finally realized at 0.9GHz

According to the microstrip transmission line theory, when the operating frequency of the array antenna is changed from 0.9GHz to 1.8GHz, the phase difference between the eight differential phase feeding stubs 7, 8, 9, 10, 11, 12, 13, and 14 becomes 90°, finally realize the phase difference between adjacent array elements T at 1.8GHz

In this embodiment, at 0.9GHz, the phase difference between adjacent array units T A vortex electromagnetic beam with mode value l=1 can be obtained; at 1.8GHz, the phase difference between each array unit T A vortex electromagnetic beam with mode value l=2 can be obtained.

The effect of this embodiment can be further illustrated by the following simulation:

1. Simulation conditions: use the electromagnetic simulation software HFSS15.0 to simulate the above array antenna model.

2. Simulation content:

Simulation 1, the return loss of the embodiment of the present invention is simulated, and its simulation result is as shown in Figure 2, as can be seen from the return loss curve diagram of Figure 2, the return loss of the array antenna of the present invention is both at 0.9GHz and 1.8GHz If it is less than -25dB, the working condition of the array antenna is good.

Simulation 2 is to simulate the far-field radiation pattern of the embodiment of the present invention at 0.9 GHz, and the simulation result is shown in Figure 3, as can be seen from the far-field radiation pattern of Figure 3, the far-field radiation pattern is in the front of the array antenna An energy depression is formed above, which conforms to the characteristics of vortex electromagnetic waves.

Simulation 3 is to simulate the far-field radiation pattern of the embodiment of the present invention at 1.8 GHz. The simulation result is shown in FIG. 4. As can be seen from the far-field radiation pattern of FIG. An energy depression is formed above, which conforms to the characteristics of vortex electromagnetic waves.

Simulation 4 is to simulate the near-field electric field distribution diagram of the embodiment of the present invention at 0.9 GHz. The simulation results are shown in Figure 5. As can be seen from the near-field electric field distribution diagram in Figure 5, when the vortex electromagnetic field modal value is 1 , the near-field electric field distribution is two orbital curves rotating clockwise.

Simulation 5 is to simulate the near-field electric field distribution diagram of the embodiment of the present invention at 1.8 GHz. The simulation results are shown in Figure 6. As can be seen from the near-field electric field distribution diagram in Figure 6, when the vortex electromagnetic field modal value is 2 , the near-field electric field distribution is four orbital curves rotating clockwise.

It can be seen from simulation 4 and simulation 5 that the near-field electric field is distributed as a plurality of clockwise orbital curves, which is consistent with the beam characteristics of orbital angular momentum of different modal values, indicating that the array antenna of the present invention can produce electromagnetic waves with good vortex electromagnetic wave characteristics .

Claims (8)

1. a kind of for generating the array antenna of bimodal vortex electromagnetic field, including 8 array elements (T), feeding network (K), Medium substrate (J), coaxial probe (D) and metal floor (G), 8 array elements (T) and feeding network (K) are printed on medium The upper surface of substrate (J), metal floor (G) are printed on the lower surface of medium substrate (J), it is characterised in that:

Each array element (T) is H-shaped patch, the first rectangular channel is provided in the center of each unit two sides, each The center on unit bottom edge is provided with the second rectangular channel, is provided with U-type groove in one end of each unit, so that each array element work Make in the two frequency points of 0.9GHz and 1.8GHz；

It is equipped with two groups of double minor matters impedance matching boxs in feeding network (K), respectively first group double minor matters impedance matching box (2,3), With second group of double minor matters impedance matching box (5,6) so that feeding network work is in 0.9GHz and 1.8GHz；

8 differences mutually feed minor matters (7,8,9,10,11,12,13,14) is additionally provided in feeding network (K), in each adjacent array list Realize that difference is mutually fed between first (T), the turning of each difference mutually feed minor matters is externally provided with the tangent line that beveling rate is p, the tangent line with turn Distance on the outside of angle is L₁, and the angle between tangent line and feeder line bottom edge is 45 °, on the inside of turning and the distance between on the outside of turning For L₂, beveling rate p=L₁/L₂, i.e., in the frequency point of 0.9GHz, mutually feed minor matters successively realize each adjacent array element to this 8 differences (T) 45 ° of the phase phase difference between, in the frequency point of 1.8GHz, mutually feed minor matters successively realize each adjacent array element to this 8 differences (T) 90 ° of the phase phase difference between；8 differences mutually feed the micro-strip that minor matters (7,8,9,10,11,12,13,14) are serpentine configuration Transmission line.

2. array antenna according to claim 1, it is characterised in that: feeding network (K) is equipped with an input port and 8 Output port, the input terminal are connect with coaxial probe (D), to realize coaxial probe (D) to the feed of feeding network (K)；This 8 Output port is successively correspondingly connected with 8 array elements (T), to realize feeding network (K) to the feed of array element (T).

3. array antenna according to claim 1, it is characterised in that: two groups of double minor matters impedance matching boxs are 2 assistant wardens connection Stairstepping impedance matching box, each length that saves is λ_0.9/ 6, wherein λ_0.9For the corresponding operation wavelength of 0.9GHz.

4. array antenna according to claim 1, it is characterised in that: two groups of double minor matters impedance matching boxs are in coaxial probe (D) above and below position, bilateral symmetry.

5. array antenna according to claim 1, it is characterised in that: First Transition minor matters (1) and the second transition minor matters (4) Above and below the position coaxial probe (D), bilateral symmetry.

6. array antenna according to claim 1, it is characterised in that: first group of double minor matters impedance matching box (2,3) is equipped with 2 A, First Transition minor matters (1) are equipped with 2, and the second transition minor matters (4) are equipped with 4, second group of double minor matters impedance matching box (5,6) Equipped with 4, every 2 transition minor matters (4) connection partners.

7. array antenna according to claim 6, it is characterised in that:

The double minor matters impedance matching boxs (2,3) of 2 of described first group, the first minor matters (2) of each of which and each First Transition branch Section (1) is correspondingly connected with, each of which second minor matters (3) is correspondingly connected with each pair of second transition minor matters (4), i.e. 2 the second minor matters (3) It is correspondingly connected with respectively with two pairs of transition minor matters (4)；

Each of described second group double minor matters impedance matching box (5,6), each of which first minor matters (5) and each second transition minor matters (4) it is correspondingly connected with, mutually feed minor matters are correspondingly connected with each of which second minor matters (6) with each pair of difference, i.e. 4 the second minor matters (6) are respectively With first pair of difference mutually feed minor matters (7,8), second pair of difference mutually feed minor matters (9,10), third to poor mutually feed minor matters (11,12), Mutually mutually feed minor matters are correspondingly connected with this four pairs differences of feed minor matters (13,14) 4th pair of difference.

8. array antenna according to claim 1, it is characterised in that: the complete phase of size of 8 array elements (T) Together, it and is equally spaced in radius as on R circumference, wherein R value is the corresponding wavelength of 1.8GHz.